Mechanically Deployed Heat Shields Open Like an Umbrella
As NASA missions to Mars continue, the spacecraft to get there are becoming larger and larger.
And to protect those vehicles against the extreme heat of entering the planet's atmosphere and decelerating in the thin Martian atmosphere will require larger heat shields.
The rocket's that launch these vehicles have limited space to accommodate the larger heat shields, so NASA has been exploring alternatives to the rigid shell construction typically found today, including inflatables.
Engineers at NASA's Ames Research Center in Silicon Valley, California, think they have a solution that is even better.
It's called ADEPT.
ADEPT is NASA's Adaptive Deployable Entry and Placement Technology. It is a mechanically deployed heat shield concept using carbon fabric -- a flexible heat shield that 'opens' like an umbrella.
It is expected that ADEPT will be used for more than just Mars probes. Venus, Jupiter, Saturn, Uranus, even Neptune could all be explored with spacecraft using this system. One reason is ADEPT will deliver payloads with a 10x reduction in peak deceleration loads.
What that means is that, to go to Venus, for example, a spacecraft with rigid aeroshells (like Apollo or MSL) would encounter a 200 – 450 g-load during entry deceleration. By using a deployable system like ADEPT, however, a large, 7 m diameter heat shield could reduce that g-load to around 30 g’s.
And, in the future, for large payloads to Mars, ADEPT can be maneuvered to deliver a precision-guided direct entry to the surface without slowing down or attempting to orbit the planet first.
Flip it inside out and it will even provide shielding and landing structure for crew and payload compartments.
As a spokesman at Ames commented:
The objective of ADEPT is to develop a semi-rigid low-ballistic coefficient aeroshell entry system concept to perform and entry descent landing (EDL) functions for planetary missions.
Mechanically deployed heat shields have been proposed for several years, but recently, Ames' engineers tested the idea. They successfully completed a heating simulation test of an ADEPT model under conditions similar to entering the Martian atmosphere.
During the test, surface temperatures on the heat shield reached 3,100 degrees Fahrenheit. Blue streaks, streaming away from the test article, from decomposition of resin-infused layers that protect the stitched joints of the carbon fabric, were seen streaming from the heat shield, adding dramatic proof of its capabilities.
The test including extensive instrumentation and photographic monitoring which will validate how the carbon fabric was able to resist the intense heat. And -- better yet -- the approach will enable further, more in depth testing that could lead to bigger and better heat shields.
The ADEPT project is led by NASA's Ames Research Center, with contributions from multiple other NASA centers. Testing, conducted by Ames' Entry Systems and Technology Division, was funded by the Game Changing Development Program within NASA's Space Technology Mission Directorate.
For more information, visit the ADEPT project page here.